Design of metal contacts for monolayer Fe₃GeTe₂ based devices

Using ab initio density functional calculations, we study the interfacial properties of the Fe₃GeTe₂ monolayer in contact with the Au, Cu, In, Cr, Ti, and Ni metal substrates. It is found that Cr, Ti, and Ni bind strongly with Fe₃GeTe₂, in contrast to Au, Cu, and In. By analyzing the density of states, charge redistribution, and tunneling barrier, it is suggested that the commonly used Au, Cu, In, and Cr electrodes are insufficient for the electron and spin injection. Ti and Ni metal substrates are proposed to have good electronic transparency to the Fe₃GeTe₂ monolayer. The Ni substrate is found to have a large spin injection to the Fe₃GeTe₂ monolayer in addition to its excellent electron injection. Our results indicate that Ni is a promising electrode for the Fe₃GeTe₂ monolayer to form current in-plane devices, thus shedding light on the optimal selection of metal electrodes for the development of next generation spintronic devices based on atomically thin nanomaterials.